WO2004110052A1 - Two-dimensional optical scanning apparatus and image display apparatus using the same - Google Patents

Two-dimensional optical scanning apparatus and image display apparatus using the same Download PDF

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Publication number
WO2004110052A1
WO2004110052A1 PCT/KR2004/001362 KR2004001362W WO2004110052A1 WO 2004110052 A1 WO2004110052 A1 WO 2004110052A1 KR 2004001362 W KR2004001362 W KR 2004001362W WO 2004110052 A1 WO2004110052 A1 WO 2004110052A1
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WO
WIPO (PCT)
Prior art keywords
axis
lens unit
cylindrical lens
light emitting
light source
Prior art date
Application number
PCT/KR2004/001362
Other languages
French (fr)
Inventor
Tae-Sun Song
Original Assignee
Tae-Sun Song
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tae-Sun Song filed Critical Tae-Sun Song
Publication of WO2004110052A1 publication Critical patent/WO2004110052A1/en

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G02B26/105—Scanning systems with one or more pivoting mirrors or galvano-mirrors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light
    • G02B26/10—Scanning systems
    • G02B26/108—Scanning systems having one or more prisms as scanning elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/18—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical projection, e.g. combination of mirror and condenser and objective
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
    • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
    • G02B6/002—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/024—Details of scanning heads ; Means for illuminating the original
    • H04N1/028—Details of scanning heads ; Means for illuminating the original for picture information pick-up
    • H04N1/02815—Means for illuminating the original, not specific to a particular type of pick-up head
    • H04N1/02845—Means for illuminating the original, not specific to a particular type of pick-up head using an elongated light source, e.g. tubular lamp, LED array
    • H04N1/02865—Means for illuminating the original, not specific to a particular type of pick-up head using an elongated light source, e.g. tubular lamp, LED array using an array of light sources or a combination of such arrays, e.g. an LED bar
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/04—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa
    • H04N1/113—Scanning arrangements, i.e. arrangements for the displacement of active reading or reproducing elements relative to the original or reproducing medium, or vice versa using oscillating or rotating mirrors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/74—Projection arrangements for image reproduction, e.g. using eidophor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3129—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM] scanning a light beam on the display screen

Definitions

  • the present invention relates to a two-dimensional optical scanning apparatus, and more particularly to a two-dimensional optical scanning apparatus having a linear light source and an elongated scanning unit which deflects and scans a light beam two-dimensionally, and an image display apparatus using the same.
  • wide-screen image display apparatuses have been popular. It is possible to classify the wide-screen image display apparatuses as a direct view type such as a CRT device, a projection type such as an LCD device, and an optical scanning type.
  • the CRT device of the direct view type produces color images when its phosphorescent surface is struck by red/green/blue electron beams in response to a color image signal having red/green/blue components.
  • the CRT device is required to have a large traveling distance of electron beams between electron guns and the phosphorescent surface, resulting in huge dimensions and a heavy weight thereof.
  • the CRT device is not suitable for the wide-screen image display apparatus.
  • the LCD projector of the projection type has an advantage of a slim size, but it has a drawback in that it is required to employ a polarizer which may incur light loss.
  • a two-dimensional optical scanning apparatus includes: a linear light source having a plurality of light emitting devices for emitting modulated light to transmit image information; a collimator lens unit converting light emitted from each light emitting device to a collimated beam; and a scanning unit having an elongated rotary polygon mirror.
  • the plurality of light emitting devices are arranged in a first axis direction perpendicular to an optic axis, and a rotary axis of the rotary polygon mirror is parallel with the first axis.
  • a two-dimensional optical scanning apparatus includes: a linear light source having a plurality of light emitting devices for emitting modulated light to transmit image information, the plurality of light emitting devices being arranged in a first axis direction perpendicular to an optic axis; a first cylindrical lens unit having a first refractive power in a plane normal to the first axis; a second cylindrical lens unit having a second refractive power in a plane which is comprised of the first axis and the optic axis; and a scanning unit having an elongated rotary polygon mirror, an rotary axis of the rotary polygon mirror being parallel with the first axis.
  • a distance between the linear light source and the first cylindrical lens unit is a focal length of the first cylindrical lens unit, and a distance between the linear light source and the second cylindrical lens unit is a focal length of the second cylindrical lens unit.
  • first and second cylindrical lens with one toric lens or anamorphic lens which has a first refractive power in a plane normal to the first axis and a second refractive power in a plane which is comprised of the first axis and the optic axis.
  • an image display apparatus includes: a linear light source having a plurality of light emitting devices for emitting modulated light to transmit image information, the plurality of light emitting devices being arranged in a first axis direction perpendicular to an optic axis; a first cylindrical lens unit having a first refractive power in a plane normal to the first axis; a second cylindrical lens unit having a second refractive power in a plane which is comprised of the first axis and the optic axis; a scanning unit having an elongated rotary polygon mirror, an rotary axis of the rotary polygon mirror being parallel with the first axis; and a screen on which light is projected from the scanning unit.
  • a distance between the linear light source and the first cylindrical lens unit is a focal length of the first cylindrical lens unit, and a distance between the linear light source and the second cylindrical lens unit is a focal length of the second cylindrical lens unit. It is possible to substitute the first and second cylindrical lens with one toric lens or anamorphic lens which has a first refractive power in a plane normal to the first axis and a second refractive power in a plane which is comprised of the first axis and the optic axis.
  • FIG. 1 is a schematic perspective view of a two-dimensional optical scanning apparatus according to a first embodiment of the present invention
  • Fig. 2 is a view illustrating a linear light source
  • Fig. 3 is a view illustrating a collimator lens unit of Fig. 1 ;
  • Fig. 4 is a view illustrating a wedge prism
  • Fig. 5 is a schematic perspective view of a two-dimensional optical scanning apparatus according to a second embodiment of the present invention.
  • Fig. 6 is a plan view in yz plane and zx plane of a part of the apparatus in Fig. 5;
  • Figs. 7 and 8 are views illustrating a rear projection type image display apparatus.
  • the two-dimensional optical scanning apparatus 10 of Fig. 1 has a linear light source
  • the linear light source 100 preferably has a plurality of light emitting devices
  • the plurality of light emitting devices 110 may be arranged in one line as shown in Fig.2(a), or in two or more lines as shown in Fig. 2(b) when high intensity or resolution is required.
  • the collimator lens unit 200 converts light from each device of the linear light source 100 to a substantially collimated beam, and may be a cylindrical lens or a toric lens.
  • the collimator lens unit 200 may be an array of a plurality of small rod lenses 120, a combination of the rod lenses 120 and ball lenses 130, or aspherical lenses 140, as shown in Fig. 3(a)-3(c), respectively. Alternatively, it may be a combination of the rod lenses and cylindrical lenses (or toric lenses).
  • a wedge prism 210 or wedged reflecting surface may be employed, as shown in Fig. 4.
  • the wedge prism 210 has a tilted reflecting surface 211 , a total reflecting surface 212 parallel with the optic axis, and a lens surface 213.
  • a separate collimator lens unit 200 may be omitted.
  • the light emitted from each light emitting device 110 reflects from the tilted reflecting surface 211 , and then internally reflects from the total reflecting surface 212 a plurality of times to decrease a diverging angle each reflection to enhance efficiency of light.
  • the rotary polygon mirror 300 has a rotating axis 310 parallel with the elongated linear light source 100.
  • the mirror 300 is elongated in a direction of the rotary axis and is rotated by a motor (not shown).
  • the two-dimensional optical scanning apparatus operates as follows.
  • Each modulated light emitted from each light emitting device 110 of the linear light source 100 passes through the collimator lens unit 200 to be converted into a collimated beam.
  • Each collimated beam is scanned by the rotary polygon mirror 300 to two-dimensional scan and display an image on the screen 500.
  • the linear light source is disposed parallel with an x-axis as shown in Fig. 1.
  • the length of the linear light source determines a dimension along the x-axis of the screen 500.
  • the dimension along a z-axis of the screen 500 is determined by a scanning angle of the rotary polygon mirror 300 and a distance between the rotary polygon mirror 300 and the screen 500.
  • the maximum dimension along the z-axis of the screen 500 is determined by the distance between the rotary polygon mirror 300 and the screen 500 as follows:
  • TL is a distance between the rotary polygon mirror and the screen
  • m is the number of mirror surfaces of the polygon mirror
  • the compensating lens is preferably used in the case that the scanning angle is large so the shape of light bundle in a center portion are quite different from that in an edge portion. When the scanning angle is large, aberrations may be generated to vary the shape of the light bundle.
  • the compensating lens is capable of compensating various optical aberrations to enhance the image quality .
  • the first embodiment is directed to an optical scanning apparatus of which scanned image has dimensions of the length of the linear light source
  • the second embodiment is directed to an optical scanning apparatus of which a scanned image is enlarged with respect to the length of the linear light source.
  • the two-dimensional optical scanning apparatus 10 has a linear light source 100, two cylindrical lens units 250 and 260, a rotary polygon mirror 300, and a compensating lens unit 400.
  • the linear light source 100 preferably has a plurality of light emitting devices 110 such as laser diodes or light emitting diodes which are arranged in a line to emit modulated red, green, and blue light in order to display an image. Similar to those of the first embodiments, the plurality of light emitting devices 110 may be arranged in one line as shown in Fig.2(a), or in two or more lines as shown in Fig. 2(b).
  • the plurality of light emitting devices 110 may be arranged in one line as shown in Fig.2(a), or in two or more lines as shown in Fig. 2(b).
  • the linear light source is disposed parallel with an x-axis and emits light along a z-axis, as shown in Fig. 5.
  • the first cylindrical lens unit 250 has a refractive power in a yz-plane
  • the second cylindrical lens unit 260 has a refractive power in a zx-plane.
  • the first cylindrical lens unit 250 is placed such that a distance between the linear light source 100 and the first cylindrical lens unit 250 is a focal length f1 of the first cylindrical lens unit 250.
  • the second cylindrical lens unit 260 is placed such that a distance between the linear light source 100 and the second cylindrical lens unit 260 is a focal length f2 of the second cylindrical lens unit 260.
  • first and second cylindrical lens units 250 and 280 are identical to first and second cylindrical lens units 250 and
  • the 260 may be substituted for a toric lens or anamorphic lens which has sagittal and tangential focal lengths which are different from each other.
  • the one toric lens or anamorphic lens may serve as the first and second cylindrical lens units simultaneously.
  • the rotary polygon mirror 300 has a rotary axis 310 parallel with the elongated linear light source 100.
  • the mirror 300 is elongated in a direction of the rotating axis, and is rotated by a motor (not shown).
  • the compensating lens unit 400 may compensate an image on a screen which is scanned by the rotary polygon mirror 300.
  • a diverging angle of the light source is very small, or when a scanning angle of the rotary polygon mirror is quite small, aberrations including a distortion becomes small to obtain a high quality of image without any compensating lens unit 400.
  • the linear light source 100 emits modulated light which diverges.
  • the light beam component which diverges in a yz plane is collimated by the first cylindrical lens unit 250, since the linear light source 100 lies on a focal point of the first cylindrical lens unit 250, as shown in Fig. 6(a).
  • the beam component in the yz plane passes through the second cylindrical lens unit 260, which does not refract the beam component in the yz plane, to proceed to the rotary polygon mirror 300.
  • the light beam component which diverges in a zx plane passes through the first cylindrical lens unit 250 to enter into the second cylindrical lens unit 260, as shown in Fig. 6(b).
  • the first cylindrical lens unit 250 does not refract the beam in the zx plane.
  • the beam component in the zx plane is collimated by the second cylindrical lens unit 260 to proceed to the rotary polygon mirror 300 since the linear light source 100 lies on a focal point of the second cylindrical lens unit 260.
  • the beam component in the zx plane becomes an oblique beam with an oblique angle according to each position of the light emitting device 110 after passing through the second cylindrical lens unit 260.
  • the two-dimensional optical scanning apparatus is capable of producing the enlarged image which is magnified in the direction of the linear light source as well as in the scanned direction.
  • the dimension parallel to the x-axis of the screen is as follows:
  • the dimension parallel to the x-axis of the screen is as follows:
  • TL is a distance from the rotary polygon mirror to the screen.
  • a dimension in another direction is determined by a scanning angle of the rotary polygon mirror 300 and the distance between the rotary polygon mirror 300 and the screen 500.
  • the maximum screen dimension which relates to the distance between the rotary polygon mirror 300 and the screen 500 is as follows: 2 x TL x tan (360° / m) where TL is a distance from the rotary polygon mirror to the screen, and m is the number of the reflecting surfaces of the rotary polygon mirror.
  • the image display apparatus may be either a rear projection type or a front projection type.
  • a screen is disposed as the screen 500 of Fig. 5 for the front projection type image display apparatus.
  • the rear projection type image display apparatus it preferably has a housing 600 in order to enhance contrast as shown in Fig. 7 or Fig. 8.
  • a transmissive screen 510 may be employed, and one or more reflectors 610, 620 may be used in order to maintain the distance between the screen 510 and the two dimensional optical scanning apparatus 10.
  • the two-dimensional optical scanning apparatus may be applied to a two-dimensional reading apparatus for reading two-dimensional information.
  • a monochromatic light source such as a laser or laser diode is employed as a light source, and an information sheet which is to be read is disposed instead of the screen in the image display apparatus.
  • the monochromatic light beam is two-dimensionally scanned and then reflected from the information sheet. The reflected light is detected by an appropriate detector.
  • the two-dimensional optical scanning device has advantages in that it has a compact size since the linear light source and the rotary polygon mirror elongated are used.
  • the apparatus is also capable of two-dimensionally scanning to reduce power consumption and noise with low-speed rotation of the rotary polygon mirror.
  • the apparatus is capable of two-dimensional scanning in different magnification as well as the same magnification as the dimension of the linear light source.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Mechanical Optical Scanning Systems (AREA)

Abstract

A two-dimensional optical scanning apparatus image display apparatus using the same is disclosed. The two-dimensional optical scanning apparatus has a linear light source, a collimator lens unit, and a scanning unit. The linear light source has a plurality of light emitting devices which are arranged in an elongated direction. The scanning unit has an elongated rotary polygon mirror which is parallel with the linear source.

Description

TITLE OF THE INVENTION
Two-dimensional Optical Scanning Apparatus and Image Display Apparatus using the same BACKGROUND OF THE INVENTION (a) Field of the Invention
The present invention relates to a two-dimensional optical scanning apparatus, and more particularly to a two-dimensional optical scanning apparatus having a linear light source and an elongated scanning unit which deflects and scans a light beam two-dimensionally, and an image display apparatus using the same.
(b) Description of the Related Art
Recently, wide-screen image display apparatuses have been popular. It is possible to classify the wide-screen image display apparatuses as a direct view type such as a CRT device, a projection type such as an LCD device, and an optical scanning type.
The CRT device of the direct view type produces color images when its phosphorescent surface is struck by red/green/blue electron beams in response to a color image signal having red/green/blue components. The CRT device is required to have a large traveling distance of electron beams between electron guns and the phosphorescent surface, resulting in huge dimensions and a heavy weight thereof.
Therefore, the CRT device is not suitable for the wide-screen image display apparatus.
The LCD projector of the projection type has an advantage of a slim size, but it has a drawback in that it is required to employ a polarizer which may incur light loss.
In the meantime, the image display apparatus of the optical scanning type has been suggested in Korean Patent No. 0366155, granted to the applicant of the present invention. Since two rotary polygon mirrors are employed to two- dimensionally scan light in the above patent, the entire optical scanning apparatus has relatively large dimensions. Further, the two rotary polygon mirrors rotate at high speeds, which increases power consumption and noise, since a substantial point light source is used as a light source.
SUMMARY OF THE INVENTION
In view of the prior art described above, it is an object of the present invention to provide a two-dimensional optical scanning apparatus being capable of scanning light two-dimensionally without any high-speed scanning unit.
It is another object of the present invention to provide a compact two- dimensional optical scanning apparatus and an image display apparatus being capable of displaying an image on a wide screen without any high-speed scanning unit.
To achieve these and other objects, as embodied and broadly described herein, a two-dimensional optical scanning apparatus includes: a linear light source having a plurality of light emitting devices for emitting modulated light to transmit image information; a collimator lens unit converting light emitted from each light emitting device to a collimated beam; and a scanning unit having an elongated rotary polygon mirror.
The plurality of light emitting devices are arranged in a first axis direction perpendicular to an optic axis, and a rotary axis of the rotary polygon mirror is parallel with the first axis.
According to another aspect of the present invention, a two-dimensional optical scanning apparatus includes: a linear light source having a plurality of light emitting devices for emitting modulated light to transmit image information, the plurality of light emitting devices being arranged in a first axis direction perpendicular to an optic axis; a first cylindrical lens unit having a first refractive power in a plane normal to the first axis; a second cylindrical lens unit having a second refractive power in a plane which is comprised of the first axis and the optic axis; and a scanning unit having an elongated rotary polygon mirror, an rotary axis of the rotary polygon mirror being parallel with the first axis.
A distance between the linear light source and the first cylindrical lens unit is a focal length of the first cylindrical lens unit, and a distance between the linear light source and the second cylindrical lens unit is a focal length of the second cylindrical lens unit.
It is possible to substitute the first and second cylindrical lens with one toric lens or anamorphic lens which has a first refractive power in a plane normal to the first axis and a second refractive power in a plane which is comprised of the first axis and the optic axis.
According to still another aspect of the present invention, an image display apparatus includes: a linear light source having a plurality of light emitting devices for emitting modulated light to transmit image information, the plurality of light emitting devices being arranged in a first axis direction perpendicular to an optic axis; a first cylindrical lens unit having a first refractive power in a plane normal to the first axis; a second cylindrical lens unit having a second refractive power in a plane which is comprised of the first axis and the optic axis; a scanning unit having an elongated rotary polygon mirror, an rotary axis of the rotary polygon mirror being parallel with the first axis; and a screen on which light is projected from the scanning unit.
A distance between the linear light source and the first cylindrical lens unit is a focal length of the first cylindrical lens unit, and a distance between the linear light source and the second cylindrical lens unit is a focal length of the second cylindrical lens unit. It is possible to substitute the first and second cylindrical lens with one toric lens or anamorphic lens which has a first refractive power in a plane normal to the first axis and a second refractive power in a plane which is comprised of the first axis and the optic axis.
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic perspective view of a two-dimensional optical scanning apparatus according to a first embodiment of the present invention; Fig. 2 is a view illustrating a linear light source; Fig. 3 is a view illustrating a collimator lens unit of Fig. 1 ;
Fig. 4 is a view illustrating a wedge prism;
Fig. 5 is a schematic perspective view of a two-dimensional optical scanning apparatus according to a second embodiment of the present invention;
Fig. 6 is a plan view in yz plane and zx plane of a part of the apparatus in Fig. 5; and
Figs. 7 and 8 are views illustrating a rear projection type image display apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings, wherein like reference numerals designate like elements throughout.
Referring first to Fig. 1 , a two-dimensional optical scanning apparatus according to a first embodiment of the present invention will be described. The two-dimensional optical scanning apparatus 10 of Fig. 1 has a linear light source
100 and collimator lens unit 200 and a rotary polygon mirror 300 which is elongated in parallel with the linear light source.
The linear light source 100 preferably has a plurality of light emitting devices
110 such as laser diodes or light emitting diodes which are arranged in a line to emit modulated red, green, and blue light for display of an image. The plurality of light emitting devices 110 may be arranged in one line as shown in Fig.2(a), or in two or more lines as shown in Fig. 2(b) when high intensity or resolution is required.
The collimator lens unit 200 converts light from each device of the linear light source 100 to a substantially collimated beam, and may be a cylindrical lens or a toric lens. The collimator lens unit 200 may be an array of a plurality of small rod lenses 120, a combination of the rod lenses 120 and ball lenses 130, or aspherical lenses 140, as shown in Fig. 3(a)-3(c), respectively. Alternatively, it may be a combination of the rod lenses and cylindrical lenses (or toric lenses).
In order to maximize the intensity efficiency of the light emitted from each light emitting device, a wedge prism 210 or wedged reflecting surface may be employed, as shown in Fig. 4. The wedge prism 210 has a tilted reflecting surface 211 , a total reflecting surface 212 parallel with the optic axis, and a lens surface 213. When the lens surface 213 can collimate light, a separate collimator lens unit 200 may be omitted. The light emitted from each light emitting device 110 reflects from the tilted reflecting surface 211 , and then internally reflects from the total reflecting surface 212 a plurality of times to decrease a diverging angle each reflection to enhance efficiency of light.
The rotary polygon mirror 300 has a rotating axis 310 parallel with the elongated linear light source 100. The mirror 300 is elongated in a direction of the rotary axis and is rotated by a motor (not shown).
The two-dimensional optical scanning apparatus according to the first embodiment of the present invention operates as follows.
Each modulated light emitted from each light emitting device 110 of the linear light source 100 passes through the collimator lens unit 200 to be converted into a collimated beam. Each collimated beam is scanned by the rotary polygon mirror 300 to two-dimensional scan and display an image on the screen 500.
Let's assume that the linear light source is disposed parallel with an x-axis as shown in Fig. 1. The length of the linear light source determines a dimension along the x-axis of the screen 500. The dimension along a z-axis of the screen 500 is determined by a scanning angle of the rotary polygon mirror 300 and a distance between the rotary polygon mirror 300 and the screen 500.
The maximum dimension along the z-axis of the screen 500 is determined by the distance between the rotary polygon mirror 300 and the screen 500 as follows:
2 x TL x tan (360° / m) where TL is a distance between the rotary polygon mirror and the screen, and m is the number of mirror surfaces of the polygon mirror.
In actuality, it is preferable to scan an image which is smaller than the maximum dimensions in order to insure a mechanical tolerance and other margins.
It is possible to place a compensating lens such as an f-θ lens between the polygon mirror 300 and screen 500 to compensate aberrations of the beam which is reflected from the rotary polygon mirror 300. The compensating lens is preferably used in the case that the scanning angle is large so the shape of light bundle in a center portion are quite different from that in an edge portion. When the scanning angle is large, aberrations may be generated to vary the shape of the light bundle.
The compensating lens is capable of compensating various optical aberrations to enhance the image quality .
Referring next to Fig. 5, a second embodiment of the present invention will be described. The first embodiment is directed to an optical scanning apparatus of which scanned image has dimensions of the length of the linear light source, while the second embodiment is directed to an optical scanning apparatus of which a scanned image is enlarged with respect to the length of the linear light source. The two-dimensional optical scanning apparatus 10 has a linear light source 100, two cylindrical lens units 250 and 260, a rotary polygon mirror 300, and a compensating lens unit 400.
The linear light source 100 preferably has a plurality of light emitting devices 110 such as laser diodes or light emitting diodes which are arranged in a line to emit modulated red, green, and blue light in order to display an image. Similar to those of the first embodiments, the plurality of light emitting devices 110 may be arranged in one line as shown in Fig.2(a), or in two or more lines as shown in Fig. 2(b).
Let's assume that the linear light source is disposed parallel with an x-axis and emits light along a z-axis, as shown in Fig. 5. The first cylindrical lens unit 250 has a refractive power in a yz-plane, while the second cylindrical lens unit 260 has a refractive power in a zx-plane. The first cylindrical lens unit 250 is placed such that a distance between the linear light source 100 and the first cylindrical lens unit 250 is a focal length f1 of the first cylindrical lens unit 250. The second cylindrical lens unit 260 is placed such that a distance between the linear light source 100 and the second cylindrical lens unit 260 is a focal length f2 of the second cylindrical lens unit 260.
It should be noted that the first and second cylindrical lens units 250 and
260 may be substituted for a toric lens or anamorphic lens which has sagittal and tangential focal lengths which are different from each other. The one toric lens or anamorphic lens may serve as the first and second cylindrical lens units simultaneously.
The rotary polygon mirror 300 has a rotary axis 310 parallel with the elongated linear light source 100. The mirror 300 is elongated in a direction of the rotating axis, and is rotated by a motor (not shown).
The compensating lens unit 400 may compensate an image on a screen which is scanned by the rotary polygon mirror 300. When a diverging angle of the light source is very small, or when a scanning angle of the rotary polygon mirror is quite small, aberrations including a distortion becomes small to obtain a high quality of image without any compensating lens unit 400.
The two-dimensional optical scanning apparatus according to the second embodiment of the present invention operates as follows:
The linear light source 100 emits modulated light which diverges. The light beam component which diverges in a yz plane is collimated by the first cylindrical lens unit 250, since the linear light source 100 lies on a focal point of the first cylindrical lens unit 250, as shown in Fig. 6(a). The beam component in the yz plane passes through the second cylindrical lens unit 260, which does not refract the beam component in the yz plane, to proceed to the rotary polygon mirror 300.
The light beam component which diverges in a zx plane passes through the first cylindrical lens unit 250 to enter into the second cylindrical lens unit 260, as shown in Fig. 6(b). The first cylindrical lens unit 250 does not refract the beam in the zx plane. The beam component in the zx plane is collimated by the second cylindrical lens unit 260 to proceed to the rotary polygon mirror 300 since the linear light source 100 lies on a focal point of the second cylindrical lens unit 260. The beam component in the zx plane becomes an oblique beam with an oblique angle according to each position of the light emitting device 110 after passing through the second cylindrical lens unit 260. Accordingly, light emitted from the linear light source 100 passes through the first and second cylindrical lens units 250 and 260 to have a narrow width in the yz plane as well as a wide width in the zx plane with the oblique angle according to the position of the light emitting device. The resultant enlarged beam is then scanned by the rotary polygon mirror 300 which is elongated along the x-axis. The compensating lens 400 may compensate aberrations of the image on the screen which is scanned by the rotary polygon mirror 300. Therefore, the two-dimensional optical scanning apparatus according to the second embodiment of the present invention is capable of producing the enlarged image which is magnified in the direction of the linear light source as well as in the scanned direction.
When each light emitting device 110 is disposed at distance H from the optic axis as shown in Fig. 6(b), the oblique collimated beam has an oblique angle θ is as follows: tan θ= H/f2 where f2 is a focal length of the second cylindrical lens unit.
Therefore, when the linear light source is parallel to the x-axis, the dimension parallel to the x-axis of the screen is as follows:
2 X f3 x tan ø = 2 x f3 x H / f2 where f3 is a focal length of the compensating lens unit. When the compensating lens unit is not used in the apparatus or when the compensating lens does not effect any change of the focal length in the apparatus, the dimension parallel to the x-axis of the screen is as follows:
2 x TL x tan θ where TL is a distance from the rotary polygon mirror to the screen.
In the above condition, a dimension in another direction (y-axis) is determined by a scanning angle of the rotary polygon mirror 300 and the distance between the rotary polygon mirror 300 and the screen 500.
The maximum screen dimension which relates to the distance between the rotary polygon mirror 300 and the screen 500 is as follows: 2 x TL x tan (360° / m) where TL is a distance from the rotary polygon mirror to the screen, and m is the number of the reflecting surfaces of the rotary polygon mirror.
In actuality, it is preferable to scan an image which is smaller that the maximum dimensions in order to insure mechanical tolerance and other margins. When the two-dimensional optical scanning apparatus according to the present invention is employed in an image display apparatus, the image display apparatus may be either a rear projection type or a front projection type. A screen is disposed as the screen 500 of Fig. 5 for the front projection type image display apparatus. In the case of the rear projection type image display apparatus, it preferably has a housing 600 in order to enhance contrast as shown in Fig. 7 or Fig. 8. A transmissive screen 510 may be employed, and one or more reflectors 610, 620 may be used in order to maintain the distance between the screen 510 and the two dimensional optical scanning apparatus 10. Although the present invention has been explained with respect to an image display device, the two-dimensional optical scanning apparatus according to the present invention may be applied to a two-dimensional reading apparatus for reading two-dimensional information. For example, a monochromatic light source such as a laser or laser diode is employed as a light source, and an information sheet which is to be read is disposed instead of the screen in the image display apparatus. The monochromatic light beam is two-dimensionally scanned and then reflected from the information sheet. The reflected light is detected by an appropriate detector.
The two-dimensional optical scanning device has advantages in that it has a compact size since the linear light source and the rotary polygon mirror elongated are used. The apparatus is also capable of two-dimensionally scanning to reduce power consumption and noise with low-speed rotation of the rotary polygon mirror.
Further, the apparatus is capable of two-dimensional scanning in different magnification as well as the same magnification as the dimension of the linear light source.
While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

WHAT IS CLAIMED IS:
1. A two-dimensional optical scanning apparatus comprising: a linear light source comprising a plurality of light emitting devices for emitting modulated light to transmit image information, the plurality of light emitting devices being arranged in a first axis direction perpendicular to an optic axis; a collimator lens unit for converting light emitted from each light emitting device to a collimated beam; a scanning unit comprising an elongated rotary polygon mirror, a rotary axis of the rotary polygon mirror being parallel with the first axis.
2. The two-dimensional optical scanning apparatus as recited in claim 1 , wherein the collimator lens unit comprising compact rod lenses or ball lenses, each lens being attached in front of each light emitting device.
3. The two-dimensional optical scanning apparatus as recited in claim 1 , wherein the collimator lens unit comprises cylindrical lenses or toric lenses, each lens being attached in front of each light emitting device.
4. A two-dimensional optical scanning apparatus comprising: a linear light source comprising a plurality of light emitting devices for emitting modulated light to transmit image information, the plurality of light emitting devices being arranged in a first axis direction perpendicular to an optic axis; a first cylindrical lens unit having a first refractive power in a plane normal to the first axis; a second cylindrical lens unit having a second refractive power in a plane which is comprised of the first axis and the optic axis; and a scanning unit comprising an elongated rotary polygon mirror, an rotary axis of the rotary polygon mirror being parallel with the first axis, wherein a distance between the linear light source and the first cylindrical lens unit is a focal length of the first cylindrical lens unit, and a distance between the linear light source and the second cylindrical lens unit is a focal length of the second cylindrical lens unit.
5. The two-dimensional optical scanning apparatus as recited in claim 4, wherein the focal length of the first cylindrical lens unit is shorter than the focal length of the second cylindrical lens unit.
6. A two-dimensional optical scanning apparatus comprising: a linear light source comprising a plurality of light emitting devices for emitting modulated light to transmit image information, the plurality of light emitting devices being arranged in a first axis direction perpendicular to an optic axis; a toric or anamorphic lens unit having a first refractive power in a plane normal to the first axis and a second refractive power in a plane which is comprised of the first axis and the optic axis; and a scanning unit comprising an elongated rotary polygon mirror, a rotary axis of the rotary polygon mirror being parallel with the first axis, wherein the first refractive power is different from the second refractive power.
7. The two-dimensional optical scanning apparatus as recited in claim 1 claim
4, or claim 6, further comprising: a compensating lens unit for compensating aberrations of light scanned.
8. The two-dimensional optical scanning apparatus as recited in claim 1 , claim
4, or claim 6, wherein the apparatus comprises two or more linear optical sources.
9. The two-dimensional optical scanning apparatus as recited in claim 1, claim
4, or claim 6, wherein the linear light source comprises wedge prisms in front of the light emitting devices.
10. An image display apparatus comprising: a linear light source comprising a plurality of light emitting devices for emitting modulated light to transmit image information, the plurality of light emitting devices being arranged in a first axis direction perpendicular to an optic axis; a first cylindrical lens unit having a first refractive power in a plane normal to the first axis; a second cylindrical lens unit having a second refractive power in a plane which is comprised of the first axis and the optic axis; a scanning unit comprising an elongated rotary polygon mirror, a rotary axis of the rotary polygon mirror being parallel with the first axis; and a screen on which the light is projected from the scanning unit, wherein a distance between the linear light source and the first cylindrical lens unit is a focal length of the first cylindrical lens unit, and a distance between the linear light source and the second cylindrical lens unit is a focal length of the second cylindrical lens unit.
11. An image display apparatus comprising: a linear light source comprising a plurality of light emitting devices for emitting modulated light to transmit image information, the plurality of light emitting devices being arranged in a first axis direction perpendicular to an optic axis; a toric or anamorphic lens unit having a first refractive power in a plane normal to the first axis and a second refractive power in a plane which is comprised of the first axis and the optic axis; and a scanning unit comprising an elongated rotary polygon mirror, a rotary axis of the rotary polygon mirror being parallel with the first axis, and a screen on which the light is projected from the scanning unit, wherein the first refractive power is different from the second refractive power.
12. The image display apparatus as recited in claim 10 or claim 11 , further comprising: at least one mirror for reflecting light scanned from the scanning unit to a predetermined direction.
13. The image display apparatus as recited in claim 10 or claim 1 1 , wherein the screen is a transmission type screen.
PCT/KR2004/001362 2003-06-09 2004-06-08 Two-dimensional optical scanning apparatus and image display apparatus using the same WO2004110052A1 (en)

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KR20030036882A KR100563917B1 (en) 2003-06-09 2003-06-09 Two-dimensional optical scanning apparatus and image display apparatus using the same

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EP1833247A1 (en) * 2004-12-28 2007-09-12 Ning Yuan Apparatus for projecting video image and method thereof
US8928720B2 (en) * 2005-10-27 2015-01-06 Hewlett-Packard Development Company, L.P. Apparatus and method of scanning light using an array of light sources
CN110913090A (en) * 2019-11-29 2020-03-24 威海华菱光电股份有限公司 Image scanning device

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CN108957619B (en) * 2018-07-25 2022-09-27 京东方科技集团股份有限公司 Light guide assembly, manufacturing method of light guide assembly and backlight source

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JPH0954263A (en) * 1995-08-10 1997-02-25 Canon Inc Laser scanning optical device

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JPS5567279A (en) * 1978-11-16 1980-05-21 Canon Inc Picture conversion unit
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JPH0954263A (en) * 1995-08-10 1997-02-25 Canon Inc Laser scanning optical device

Cited By (4)

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Publication number Priority date Publication date Assignee Title
EP1833247A1 (en) * 2004-12-28 2007-09-12 Ning Yuan Apparatus for projecting video image and method thereof
EP1833247A4 (en) * 2004-12-28 2010-04-07 Ning Yuan Apparatus for projecting video image and method thereof
US8928720B2 (en) * 2005-10-27 2015-01-06 Hewlett-Packard Development Company, L.P. Apparatus and method of scanning light using an array of light sources
CN110913090A (en) * 2019-11-29 2020-03-24 威海华菱光电股份有限公司 Image scanning device

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KR100563917B1 (en) 2006-03-23

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